title: White matter/gray matter contrast changes in chronic and diffuse traumatic brain injury.
abstract: Signal-intensity contrast of T1-weighted magnetic resonance imaging scans has been associated with tissue integrity and reported as a sign of neurodegenerative changes in diseases such as Alzheimer's disease. After severe traumatic brain injury (TBI), progressive structural changes occur in white (WM) and gray matter (GM). In the current study, we assessed the signal-intensity contrast of GM and WM in patients with diffuse TBI in the chronic stage to (1) characterize the regional pattern of WM/GM changes in intensity contrast associated with traumatic axonal injury, (2) evaluate possible associations between this measure and diffusion tensor image (DTI)/fractional anisotropy (FA) for detecting WM damage, and (3) investigate the correlates of both measures with cognitive outcomes. Structural T1 scans were processed with FreeSurfer software to identify the boundary and calculate the WM/GM contrast maps. DTIs were processed with the FMRIB software library to obtain FA maps. The WM/GM contrast in TBI patients showed a pattern of reduction in almost all of the brain, except the visual and motor primary regions. Global FA values obtained from DTI correlated with the intensity contrast of all associative cerebral regions. WM/GM contrast correlated with memory functions, whereas FA global values correlated with tests measuring memory and mental processing speed. In conclusion, tissue-contrast intensity is a very sensitive measure for detecting structural brain damage in chronic, severe and diffuse TBI, but is less sensitive than FA for reflecting neuropsychological sequelae, such as impaired mental processing speed.
authors.affiliation: 1 Department of Psychiatry and Clinical Psychobiology, University of Barcelona , Barcelona, Spain .
authors.forename: Eva M
authors.initials: EM
authors.lastname: Palacios
authors.forename: Roser
authors.initials: R
authors.lastname: Sala-Llonch
authors.forename: Carme
authors.initials: C
authors.lastname: Junque
authors.forename: Teresa
authors.initials: T
authors.lastname: Roig
authors.forename: Jose M
authors.initials: JM
authors.lastname: Tormos
authors.forename: Nuria
authors.initials: N
authors.lastname: Bargallo
authors.forename: Pere
authors.initials: P
authors.lastname: Vendrell
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000150:complications / Q000473:pathology* / Q000523:psychology; D002908:Chronic Disease; D003072:Cognition Disorders / Q000209:etiology / Q000523:psychology; D056324:Diffusion Tensor Imaging; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009483:Neuropsychological Tests; D055815:Young Adult